HID: wacom: Short-circuit processing of touch when it is disabled

Avoid doing unnecessary work when touch is disabled by detecting this
condition and returning early. Note that the probe process sends GET
FEATURE requests to discover e.g. HID_DG_CONTACTMAX, so we can't start
ignoring touch reports until probe finishes.
Signed-off-by: Ping Cheng <ping.cheng@wacom.com>
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/wacom_sys.c

@@ -2797,6 +2797,7 @@ static int wacom_probe(struct hid_device *hdev,
 				 error);
 	}
 
+	wacom_wac->probe_complete = true;
 	return 0;
 }
 

drivers/hid/wacom_wac.c

@@ -2584,6 +2584,12 @@ static void wacom_wac_finger_event(struct hid_device *hdev,
 	unsigned equivalent_usage = wacom_equivalent_usage(usage->hid);
 	struct wacom_features *features = &wacom->wacom_wac.features;
 
+	/* don't process touch events when touch is off */
+	if (wacom_wac->probe_complete &&
+	    !wacom_wac->shared->is_touch_on &&
+	    !wacom_wac->shared->touch_down)
+		return;
+
 	if (wacom_wac->is_invalid_bt_frame)
 		return;
 
@@ -2633,6 +2639,12 @@ static void wacom_wac_finger_pre_report(struct hid_device *hdev,
 	struct hid_data* hid_data = &wacom_wac->hid_data;
 	int i;
 
+	/* don't process touch events when touch is off */
+	if (wacom_wac->probe_complete &&
+	    !wacom_wac->shared->is_touch_on &&
+	    !wacom_wac->shared->touch_down)
+		return;
+
 	wacom_wac->is_invalid_bt_frame = false;
 
 	for (i = 0; i < report->maxfield; i++) {

drivers/hid/wacom_wac.h

@@ -337,6 +337,7 @@ struct wacom_wac {
 	int tool[2];
 	int id[2];
 	__u64 serial[2];
+	bool probe_complete;
 	bool reporting_data;
 	struct wacom_features features;
 	struct wacom_shared *shared;